The invention pertains generally to production of oxygen and absorption of carbon dioxide and in particular to air-revitalization materials.
Fundamentally, a closed-circuit emergency breathing device supplies oxygen to the breathing air and removes carbon dioxide from the air. One approach has been to combine heavy bulky air or oxygen cylinders with canisters containing caustic alkali or soda lime for carbon dioxide removal. Another approach has been to use a compound or composition which chemically supplies oxygen and absorbs carbon dioxide.
For a compound or composition to be useable for the purpose of both absorbing carbon dioxide and producing oxygen, the compound or composition must be inexpensive and readily obtainable and have a high rate of carbon dioxide absorption and oxygen evolution, an O.sub.2 /CO.sub.2 ratio of approximately one, a low rate of heat evolution, a low toxicity, a high degree of safety, and a low requirement for humidity and temperature for oxygen effervesence with a high threshold for fusion due to humidity or temperature.
Potassium superoxide is the most widely used material for air revitalization. It represents the best compromise known today. The disadvantages of potassium superoxide are fusion, a large heat evolution, causticity, a high O.sub.2 /CO.sub.2 ratio, and a poor overall efficiency. Fusion is the major disadvantage. In many cases, only 50-60% of the potassium superoxide is useable because of fusion. If fusion could be eliminated, the useable work period could be extended nearly twofold. Elimination of fusion would also permit a change in canister design to a simpler configuration.